This layer displays the amount of toxic releases based on the Environmental Protection Agency (EPA) Toxics Release Inventory (TRI), a national program which tracks the management of over 650 toxic chemicals that pose a threat to human health and the environment. Facilities must report how each chemical is managed through recycling, energy recovery, treatment, and releases to the environment. A “release” of a chemical means that it is emitted to the air or water, or placed in some type of land disposal. The information submitted by facilities to the EPA and states is compiled annually as the Toxics Release Inventory or TRI, and is stored in a publicly accessible database ( Envirofacts. For more information, please visit the EPA Toxics Release Inventory web page.
Safe Drinking Water Information System Sites
This layer displays the locations of a subset of the Environmental Protection Agency (EPA) Safe Drinking Water Information System (SDWIS) sites. The SDWIS contains information about public water systems and their violations of EPA’s drinking water regulations. Data can be accessed through the EPA’s Clip N Ship map application. For more information, please visit the Safe Drinking Water Information System web page.
Air Quality System Sites
This layer displays the locations of air quality monitoring stations in the United States. The Air Quality System (AQS) contains ambient air pollution data collected by EPA, state, Local, and tribal air pollution control agencies from thousands of monitoring stations. AQS also contains meteorological data, descriptive information about each monitoring station (including its geographic location and its operator), and data quality assurance/quality control information. For more information, please visit the EPA Air Quality System web page.
Ecoegions
Ecoregions are identified by analyzing the patterns and composition of biotic and abiotic phenomena that affect or reflect differences in ecosystem quality and integrity (Omernik 1987, 1995). These phenomena include geology, landforms, soils, vegetation, climate, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. A Roman numeral classification scheme has been adopted for different hierarchical levels of ecoregions, ranging from general regions to more detailed:
Level I – 12 ecoregions in the continental U.S.
Level II – 25 ecoregions in the continental U.S.
Level III -105 ecoregions in the continental U.S.
Level IV – 967 ecoregions in the conterminous U.S.
Explanations of the methods used to define these multi-agency ecoregions are given in Omernik and Griffith (2014), Omernik (1995, 2004), and CEC (1997).
Air Quality – Ozone Levels (O3) by Census Tract, 2015
This layer displays the daily average concentration of ozone and the percentage of days with concentrations of ozone above the National Ambient Air Quality Standard (NAAQS) of 0.075 parts per million in 2015.
Air Quality – Fine Particulate Matter (PM2.5) by Census Tract, 2016
This layer displays the daily average concentration of fine particulate matter and the percentage of days with concentrations of fine particulate matter above the National Ambient Air Quality Standard (NAAQS) of 35.0 micrograms per cubic meter in 2016.